The present disclosure relates to a method of estimating a life, for example, of a lithium ion secondary battery or the like, to a life estimation device, for example, for a lithium ion secondary battery or the like, to an electric vehicle, and to an electric power supply apparatus.
As an electric power source in a power field including, for example, an electric vehicle, a hybrid vehicle, an electric motorcycle, and an electric power-assisted bicycle or in an electric storage field including, for example, load leveling, peak shift, and backup, a lithium ion secondary battery has been widely used.
In using the secondary battery in the power field or the electric storage field, it is largely necessary to accurately estimate a life of the secondary battery. One reason for this is that, in the case where a battery life is wrongly estimated longer than actual life and the battery life expires while in use of an apparatus, it may lead to a severe damage or a severe accident. Another reason for this is that, in contrast, in the case where the battery life is estimated excessively short, the battery is renewed unnecessarily. Further, since a battery is built into a large-scale system as part thereof, it is not necessarily possible to renew an old battery anytime. In such a system, it is necessary to renew the old battery according to a plan while previously considering a usage state and the like based on an estimated battery life. From the foregoing points, an accurate method of estimating a life of a battery has been strongly desired.
For example, in Japanese Unexamined Patent Application Publication No. 2007-322171 (JP2007-322171A), a technology to calculate degradation level and a remaining capacity of an automotive battery is disclosed. Further, it has been known that a full-charge capacity is estimated from variation in internal resistance of a battery and voltage drop of the battery.